Alt? Delco 12si vs 10 si?

Okay When I rebuilt my engine I used a Delco Remi 10si to replace the orginal unit that was fried.

Im looking at going to an electric fan, and getting rid of the fixed fan since I can't stuff a clutched fan into the engine bay with the HEI, just cant get the room.

Anyone know if there is a big differnce in size with the 12si vs the 10si? I know the 10si was a direct swap offering 63amps, the 12si offers 105 amps. Im worried about amp draw with electronics and an electric fan and I don't know if 63 Amps will cut it.

 

I've heard of this issue with HEI/fan clearance before but for some it doesn't seem to be an issue or they just don't mention it. I'd like to go HEI but not electric fan.

Also, I'm looking at going 12SI too, cuz I think the reg in my 10 is dead and I have some 12s around.

 

I have a 10SI with a 105 amp stator I found on Ebay. I think the Mad electrical link above addresses the issue of overheating with the higher amp options on the 10SI but I am not running high draw options like fan or fuel pump, I think in your situation I would go with the 12SI.

 

You need to add up your total load that could possibly be running continuously. That will determine what size alt you will need. The amp output of an alternator is not continuous duty. In other words a 63 amp alt cannot put out 63 amps for very long. Few minutes at most and then it fries..

 

I searched the previous threads viewed the websites on the threads and I have just rewired my 69 cj5 w/v6. The only thing extra on the jeep is a AM/FM radio, a DUI distributor, and up graded the head lights to the a good Silvana sealed halagon. Planning on going wih a 10si or 12si. I removed the motorola 37amp alternator and regulator. Should I go with 10si or 12si? Will these fit the bracket without any modifications? Which clock position is the alternator at?
Thanks in advance,
Mike

 

If you want to stay with Motorola, they do make that same size in a 60 amp. The red plate on the back will have two diodes in it versus one for the 37. If you decide to go Delco, just mount it on the existing bracket but you my have to make spacer and washer changes to line up belt. The clocking on the Delco is easier at 12 o'clock.

 

OK, Thanks

 

Alternator loads are discussed above but I did not see any mention of an electric winch. A winch will cause the alternator to run at full capacity while in use and for a period of time afterward as it recharges the battery. All winches I have worked with will draw even more current than a 160 amp alternator will produce, the extra draw supplied by the battery. If you have or are considering an electric winch-go the 12SI route.

 

Can also use a CS series alt. Very similar to the SI series. My CS I will run is a 144 amp unit. Another choice if you need to run a winch. And a lot less expensive and you can get parts/replacment at any autoparts store.